The invention relates to earthquake alarms, and more particularly to a small alarm device having a ball on a perch electrically connected to a power source and a sound emitter which is actuated by an electric circuit being closed when the ball falls off the perch, due to earthquake tremors.
It is well known that earthquakes often present great dangers, especially if they occur at night, when people are asleep and are not aware of early warnings, such as the early small tremors that usually precede a serious major earthquake, also called foreshocks. Foreshocks may precede an earthquake by hours or days.
Earthquake measuring and warning devices are well known in the form of seismographs, that sense and record earthquakes and may provide early warnings in cases wherein the earthquake is preceded by foreshocks. Seismographs, however, are typically large and expensive scientific instruments that are not available to ordinary people.
A small motion detection device is known from U.S. Pat. No. 4,124,841, which shows a small metallic pin standing on one end atop a battery, and, in case a tremor is detected, topples and closes an electric circuit. The latter device, however, has the drawback that the small pin when toppled only provides a small and unreliable contact pressure and therefore is not always a reliable warning.
It is, therefore, an object of the instant invention to provide an earthquake sensing device that is highly sensitive and reliable, yet is inexpensive in construction.